Efficacy of Chemical Treatments Against Murine Norovirus, Feline Calicivirus, and MS2 Bacteriophage

Abstract

Human noroviruses pose an emerging public health threat, and despite stringent control strategies, variant strains continue to spread and cause disease outbreaks. Routinely used chemical sanitizers, such as sodium hypochlorite though effective on food contact surfaces, require high concentrations to cause reduction in enteric viral titers. The aim of this study was to evaluate the efficacy of trisodium phosphate (TSP) against three human enteric virus surrogates, murine norovirus (MNV-1), feline calicivirus (FCV), and bacteriophage MS2 in comparison to routinely used sanitizers. Three concentrations of TSP (1%, 2%, and 5%) at different contact times (30 sec and 1 min) were evaluated against the surrogate viruses individually inoculated on formica coupons. Our results showed that 5% TSP was effective in obtaining a >or=6 log(10) PFU reduction for MNV-1, FCV, and MS2 after a contact time of only 30 sec or 1 min similar to 10% household bleach (0.6% sodium hypochlorite, 5000 ppm available chlorine) for high titers of FCV and MS2, and with approximately 5 log(10) reduction after either 30 sec or 1 min on low viral titers. However, 2% TSP for 1 min resulted in >or=6 log(10) PFU reduction for FCV and MS2, but only a 1.05 log(10) PFU reduction for MNV-1 at high titers, with similar results after 30 sec. Decreasing TSP levels to 1% reduced FCV by approximately 2.65 log(10) PFU, MS2 by 4.5 log(10) PFU at high titers, and no reduction for MNV-1 after 30-sec or 1 min contact. Glutaraldehyde (2%) reduced FCV and MNV-1 titers by approximately 6 log(10) PFU; however, MS2 was reduced by only 3.22 and 3.74 log(10) PFU after 30 sec and 1 min, respectively, while 70% ethanol was not effective in reducing the three viruses at either high or low titers at both contact times. Alternative control strategies using TSP with short contact times should benefit the food industry in reducing norovirus transmission.